I imagine the white book (multimedia stuff) and the nublue book (a fair
bit of system technology detail) would both be useful. I presume you're
going to be looking at much of the stuff in the linux based PVR recently
slashdotted? I'd be inclined to do very similar hardware (since it's so
cheap - hell, Fry's had 120Gb discs for $189 a few weeks ago!) and just
do the software in Squeak instead of perl or whatever they used.
Squeak can handle mp3 & mpeg video, speech generation ,sound sampling
etc but I don't know what divx & wma are so who knows if they're usable.

Getting a decent video quality on a TV screen will be interesting. You
might want to investigate working with vector graphics rather than
bitmaps, scaling up will be easier.

I was dreaming about doing something like this myself, but even though
it would be pretty cheap I still can't afford it :-( Perhaps the
trickiest part is all the legal stuff. I'm quite sure you'll be breaking
enough laws to get multiple death sentences if the evil maniacs at ##AA
have their way.

tim